Electro active elastic compression bandage

ABSTRACT

This invention relates to an elastic bandage for supporting a body extremity such as a leg. Such bandages are used to overcome problems with fluid retention and swelling in the legs, occurring as a consequence of varicose veins, vascular incompetence, pregnancy, etc. It is a task of this invention to supply an active support for a body extremity such as a leg, which can be used by a person underneath the clothes and will not reduce the mobility of the patient. This task is solved in that an elastic bandage comprises an elastic layer for surrounding a body extremity to exert compressive force on the extremity, the bandage being, at least partly, formed by elastomeric actuation elements, whereby electrical control of the compressive force is possible, and where the control is due to a signal from some sensing system.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is entitled to the benefit of and incorporates byreference essential subject matter disclosed in International PatentApplication No. PCT/DK2004/000123 filed on Feb. 24, 2004 and DanishPatent Application No. PA 2003 00277 filed Feb. 24, 2003.

FIELD OF THE INVENTION

This invention relates to an elastic bandage for supporting a bodyextremity such as a leg. Such bandage are used to overcome problems withfluid retention and swelling in the legs, occurring as a consequence ofVaricose veins, vascular incompetence, pregnancy, etc.

BACKGROUND OF THE INVENTION

Supporting stockings used to overcome the described problems are knownin a lot of variations, and are on the market in a lot of models andsizes. However, they are all passive, meaning that they are producedwith a given elasticity that will decrease over time. Typically, supportstockings can be used for about 6 months, whereafter they have lost themajor part of their elasticity.

Support stockings that are inflatable are also known, and they are ableto add a well-adjusted compressive force to a body extremity such as aleg. A pneumatic device inflates each compartment in the stocking to agiven level of pressure, and this pressure is maintained for a givenperiod. This type of stockings is, however, only useable in a controlledenvironment, like a hospital or in the home of a permanently sickperson, and is only to be used during periods where the person is in aresting position.

All these kinds of stockings may be called passive, since they give apredetermined compressive force being constant, except for loosingelasticity due to wear. An advantage could be obtained if thecompressive forces were controllable in some way. This is the case inU.S. Pat. No. 6,123,681, where the stocking contains polymer of the kindconstricting if exposed to some stimulus, preferable electric. Bysplitting the polymer into a plurality of strips, each being controlledindividually, compressive forces may be generated sequentially along thelength of the stocking to stimulate fluid flow, such as blood. The powersource making the stimulations is then possible programmed in some way,like to make the individual polymer strips constrict in a cyclic order.

SUMMARY OF THE INVENTION

It is a task of this invention to supply an active support for a bodyextremity such as a leg, which can be used by a person underneath theclothes and will reduce mobility of the patient, so that the actuationelements build into the stocking may operate in a two-way communication,where stimulations are in response to the actual state of the stockingitself, the actuation elements working as sensors too. An alternativepossibility is to stimulate in response to signals from some externalsensor, perhaps registering the heart rate, the blood flow, bodytemperature, moist under the stocking due to sweat or other parameters.It is as an example possible to synchronise the actuation of thestocking with the heart rate in such a way that the stocking is relaxedduring the systolic period to allow free flow in the arteries, while thecontraction takes place during the diastolic period in order tostimulate peristaltic flow in the veins. This task is solved in that anelastic bandage comprises an elastic layer for surrounding a bodyextremity to exert compressive force on the extremity, where the bandageis, at least partly, formed by elastomeric actuation elements,electrical control of the compressive force being possible.

Elastomeric actuators have recently become known, and exist in differenttypes and based on different principles. One such elastomeric actuatortype is known from DE 100 54 247, where a corrugated elastomeric core issupplied with an electrode on each side, vaporised onto basically thewhole of the core material in a thin layer. The electrode will followthe corrugation of the core, and hereby provide a higher deformabilityin a direction crossing the corrugation than in a direction along thecorrugation, referred to as compliant electrodes or mechanicalanisotropic properties. Placing such elastomeric elements inside or aspart of a bandage will provide an elastic bandage that is electricallycontrollable, if the direction of high deformability is the onesurrounding the extremity. The elastomeric actuation elements have theability that they expand their length when a voltage are applied, unlikeU.S. Pat. No. 6,123,681 where the polymers constrict when affected by astimulation.

In the forthcoming actuation elements is to be understood as any elasticelements able to react due to some stimulation, preferable electric, andelastomeric actuation elements is to be understood as any such systemsas mentioned above consisting of an elastomer with electrodes on the topand bottom sides.

In one embodiment of the invention the bandage can be formed as astocking to be put on the extremity. Hereby is achieved that the bandagecan be made with a shape corresponding to the extremity, the compressiveforce being equally disposed over the whole of the extremity surroundedby the bandage in a not electrically controlled situation.

In another embodiment of the invention the bandage can be formed as asheet to be wrapped around the extremity. Hereby is achieved that thebandage can be used as an ordinary bandage, on any person and on anyextremity, only with the compressive force control as an additionalfeature. Additionally, it can be achieved that open stockings, like theones used by athletics as knee-support, can be put on easily by means ofband of Velcro TM or a zip that will be properly placed on stockings toallow the stocking to be put on easily. This easily-put-on stocking isdisclosed in U.S. Pat. No. 5,520,630, only without the electricallycompressive force control.

In a specific embodiment of the invention the bandage as in U.S. Pat.No. 6,123,681 comprises separate controllable elastomeric actuationelements, formed along the extremity when said bandage is surroundingit, hereby giving the possibility of performing a peristaltic movementalong the extremity. Separate controllable elastomeric actuationelements will have the effect that each small area comprising oneseparate element will be controllable without having any influence onall other areas. Controlling all elements in a one-by-one manner willthus give a peristaltic movement along the bandage, and thus along theextremity.

The object of this invention could further be achieved in that a systemfor adding compressive force to a body extremity consists of an elasticbandage as previously described and a control unit, the control unitbeing electrically connected to electrodes on each separate controllableelastomeric actuation element.

In one embodiment of the invention the system could further comprise asensor capable of producing a signal representative for the bloodcirculation through the body extremity, or some other parameter like thebody temperature or the sweating underneath the stocking. Hereby isachieved that the compressive force on the extremity from the bandagecan be measured by the control unit, a compressive force control beingobtainable.

Preferably, the control unit is able to supply an adjustable voltage tothe electrodes on each separate controllable elastomeric actuationelement. Hereby compressive force control of each element can beachieved.

It could be preferable that the control unit adjusts the voltage withreference to the capacitance of each separate controllable elastomericactuation element. Hereby is achieved that the compressive force betweenthe two electrodes on each elastomeric element is sensible, and thuscontrollable, meaning that the force compression on the extremity isroughly sensible, depending on volume variations of the extremity duringthe day.

In a specific embodiment of the invention the control unit could adjustthe voltage in order to obtain a given capacitance of each separatecontrollable elastomeric actuation element. In a further specificembodiment the given capacity could be adjusted with reference to thesensor, hereby adjusting the compressive force of the elastic bandagewith reference to blood circulation through the body extremity. Thiswill provide a bandage system that could be optimised with respect toblood circulation, so that maximum pressure is applied to the extremitywithout preventing blood circulation to body elements after theextremity in direction from the heart.

BRIEF DESCRIPTION OF THE DRAWINGS

Now having described the invention in general terms a specificembodiment of the invention is to be disclosed with reference to thedrawings, showing:

FIG. 1: is a principle view of a bandage with control unit and sensor,the bandage surrounding a body extremity indicated with dotted lines.

FIG. 2: is a principle view of a bandage, made with separatecontrollable elastomeric elements.

FIG. 3: is a principle view of a corrugated elastomeric element.

FIG. 4: is a principle view of a corrugated elastomeric element.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 3 indicates a corrugated elastomeric actuator 1, where thecorrugation 2 has a square shape. The corrugation runs in theY-direction according to the indicated system of co-ordinates, and theX-direction is running across the corrugation. Separate electrodes havebeen vaporised onto the top surface 3 and the bottom surface 4, wherebyan electrical field-can be applied between the two electrodes. When thetwo electrodes are forced towards each other, due to the electricalfield, the elastomeric core material will be squeezed in theZ-direction, and due to volume preservation it will increase in theZ-direction, leading to an increase in the X-direction, the Y-directionor both. The corrugation combined with the electrode will, however, makethe X-direction far more deformable than the Y-direction, and theincrease will therefore only be in the X-direction. This has previouslybeen referred to as compliant electrodes or mechanical anisotropicproperties.

The square shaped corrugation is just an example, and in FIG. 4 awave-shaped corrugation is indicated. The principle is, however, thesame, the structure has compliant electrodes or mechanical anisotropicproperties.

The force and displacement, which one element from FIG. 3 or 4 is ableto deliver, are of course depending on the material and on the level ofthe electrical field. From U.S. Pat. No. 5,977,685 is it known tolaminate more elements together, the laminated stack of elements beingable to deliver a force and displacement also depending on the number ofelements in the stack, meaning that force and displacement within alarge area can be obtained.

An embodiment of the invention is indicated in FIG. 1, where a stocking8 surrounds a body extremity 7, for example, the lower part of a leg.The stocking is made with elastomeric actuators like the one in FIGS. 3and 4, and the electrodes of all actuators are connected in parallelinside the stocking, and only two electrodes 10 are lead from thestocking to a control unit 9. The control unit comprises a battery, bymeans of which an electrical field is applied to the electrodes of allactuators. The level of the electrical field is controlled bycontrolling the level of the voltage supplied from the control unit 9 tothe electrodes, and the level of the voltage is controlled in accordancewith a signal from a sensor 11, which communicates a signalcorresponding to the blood circulation through the extremity 7 to thecontrol unit via the connection 12.

FIG. 2 indicates a specific embodiment of the invention. The stocking 18is surrounding the extremity 7, and the elastomeric actuators are placedin bands 13, 14, 15 and so on. Each band 13, 14, 15 is individuallycontrollable from a control unit not shown in FIG. 2. This means that aperistaltic movement in the direction indicated by the arrow 16 can bemade simply by adding a compressive force to the bands one by one. As anexample, a compressive force should be added to band 15, then to band14, then to band 13 and so on.

While the present invention has been illustrated and described withrespect to a particular embodiment thereof, it should be appreciated bythose of ordinary skill in the art that various modifications to thisinvention may be made without departing from the spirit and scope of thepresent invention.

1. An elastic bandage comprising: an elastic layer for surrounding abody extremity to exert compressive force on said extremity, and beingat least partly formed by actuation elements that is controllable intheir compressive force when stimulated, wherein said compressive forceis at least roughly sensible, so that said actuation elements mayoperate in a two-way communication, also operating as sensors of theirown actual state of compressive force.
 2. The elastic bandage accordingto claim 1, wherein said bandage is, at least partly, formed byactuation elements, wherein said actuation elements will reduce thecompressive forces when activated by stimulation.
 3. The systemaccording to claim 2, including a control unit regulating thecompressive force of the actuation elements, wherein the control unitadjusts the compressive force with reference to the actual state of eachcontrollable actuation element.
 4. The system according to claim 2,wherein said elastic bandage contains actuation elements placed inbands, and where said control unit is able to supply an individualadjustable stimulation to each separate actuation element band.
 5. Theelastic bandage according to claim 1, wherein said bandage is, at leastpartly, formed by elastomeric actuation elements containing electrodeson the top and bottom surfaces, electrical control of the compressiveforce being possible.
 6. The elastic bandage according to claim 5,wherein the top and bottom surfaces of the elastomeric actuationelements are corrugated.
 7. The system according to claim 6, whereinchanging a capacitance does said adjustment of the compressive force. 8.The system according to claim 7, wherein said signal from said controlunit is a voltage.
 9. The system according to claim 8, wherein saidcontrol unit adjusts said signal in order to keep a given constantcapacitance of each separate controllable actuation element. 10.(canceled)
 11. (canceled)
 12. A system comprising: an elastic bandagehaving an elastic layer for surrounding a body extremity to exertcompressive force on said extremity, and being at least partly formed byactuation elements controllable in their compressive force whenstimulated, wherein said compressive force is at least roughly sensible,so that said actuation elements may operate in a two-way communication,also operating as sensors of their own actual state of compressiveforce, wherein said bandage is, at least partly, formed by actuationelements, wherein said actuation elements will reduce the compressiveforces when activated by stimulation; and a control unit regulating thecompressive force of the actuation elements, wherein the control unitadjusts the compressive force with reference to the actual state of eachcontrollable actuation element.
 13. The system according to claim 12,wherein said elastic bandage includes actuation elements placed inbands, and wherein said control unit is able to supply an individualadjustable stimulation to each separate actuation element band.
 14. Asystem comprising: an elastic bandage having an elastic layer forsurrounding a body extremity to exert compressive force on saidextremity, and being at least partly formed by actuation elementscontrollable in their compressive force when stimulated; wherein saidcompressive force is at least roughly sensible, so that said actuationelements may operate in a two-way communication, also operating assensors of their own actual state of compressive force; wherein saidbandage is, at least partly, formed by elastomeric actuation elementsincluding electrodes on the top and bottom surfaces, electrical controlof the compressive force being possible; wherein the top and bottomsurfaces of the elastomeric actuation elements are corrugated; andwherein changing a capacitance does said adjustment of the compressiveforce.
 15. The system according to claim 14, wherein said signal fromsaid control unit is a voltage.
 16. The system according to claim 15,wherein said control unit adjusts said signal in order to keep a givenconstant capacitance of each separate controllable actuation element.